Single-Stage Boost-Buck PFC Converter with Soft-Switching Operation and Ripple-Free Output Current

Abstract

In this paper, a single-stage boost-buck power-factor-correction (PFC) converter with soft-switching operation and ripple-free output current is proposed. In order to obtain high power factor, a boost PFC cell is operated in discontinuous conduction mode (DCM) with a fixed switching frequency according to the load condition. For the ripple-free output current, a buck inductor is replaced with a coupled inductor and an auxiliary capacitor. The boost PFC cell and the buck converter share a main switch and a self-driven synchronous rectifier (SR). By turning the SR off after a short delay, the main switch is turned on under zero-voltage-switching (ZVS) condition. Since the conduction loss on the SR is reduced and there is no switching loss on the main switch, the power-conversion efficiency is improved. The maximum efficiency of the proposed converter 93.37% is measured at 130vac. To verify the performance of the proposed converter, theoretical analyses, design procedures, and experimental results from a 80V and 100W prototype are presented.